Primer for use with caseless ammunition



April 7, 1970 o. MACK, JR 3,504,629

PRIMER FOR USE WITH CASELESS AMMUNITION Filed Dec. 28, 1967 JAMES O. MACK JR INVENTOR BY IM ATTORNEY United States Patent US. Cl. 102-38 8 Claims ABSTRACT OF THE DISCLOSURE A combustible primer is provided for a round of caseless ammunition in the form of a ring secured in 'an annular cavity in the base of the propellant charge of the caseless round.

This invention relates to a novel primer for use with caseless ammunition. More particularly, this invention relates to a round of caseless ammunition wherein a combustible primer in the form of a ring is secured in an annular cavity in the base of the propellant charge.

One of the major problems in the development of caseless ammunition has been the poor reliability of the caseless round. The poor reliability of the round has been chiefly attributed to the combustible primer. Improper functioning of the combustible primer can cause both misfires and poor ballistic performance of a fired round due to insufficient break up of the propellant charge. Attempts to increase reliability of the combustible primer have included addition of highly sensitive explosive materials to the priming mixture.

It is an object of this invention to provide a highly reliable, low cost combustible primer for a round of caseless ammunition employing standard primer mixtures.

It is another object of this invention to provide a reliable round of caseless ammunition having good ballistic performance.

Other objects of this invention will, in part, be obvious and will, in part, appear hereinafter. For a complete understanding of the nature and the objects of this invention, reference is made to the following detailed description and drawings.

In accordance with this invention, there is provided a round of caseless ammunition having in combination a propellant charge having an annular cavity in its base, a combustible primer secured in said annular cavity, and a projectile secured to the propellant charge.

FIG. 1 illustrates a. vertical section of a longitudinal view of a round of caseless ammunition having a combustible primer secured in an annular cavity in the base of the propellant charge.

FIG. 2 illustrates a rear view of the caseless round of FIG. 1 taken along line AA.

FIG. 3 illustrates a vertical section of a longitudinal view of another embodiment of a caseless round having a combustible primer secured in an annular cavity in the base of the propellant charge.

In FIG. 1 a propellant charge is shown having an axial bore 12 throughout. The propellant charge .10 has an annular cavity 14 in its base. The annular cavity 14 is filled with a standard priming mixture 16 and sealed with a waterproof combustible seal 18. A projectile 20 is secured within the axial bore 12 of the propellant charge.

The round of caseless ammunition described in FIG. 1

. is the preferred embodiment of this invention. The wall of propellant formed by the axial bore in the propellant charge surrounds the projectile. In this embodiment the entire length of the projectile is surrounded by propellant.

The round of caseless ammunition described, someice times referred to as a telescoped round, is shown in the loaded position in the chamber 22 of a firearm. The forward edges '24 of the propellant charge 10 are positioned against the neck 26 of the firearm.

In a firing sequence, the projectile 20 is moved forward into firing position 28 by the forward movement of a reciprocating bolt 30. The reciprocating bolt 30 has a bolt extension 32 with a reduced diameter which enters into the bore 12 of the propellant charge, contacts the base of the projectile 34, and moves the projectile 20 into firing position 28. In this position 28 substantially forward obturation of the projectile is accomplished. The forward action of the bolt 30 is controlled by a linkage in the bolt (not shown). The weapon design is such that when the bolt reaches its forward position, the propellant charge is at the loaded position with its forward edges 24 against the neck 26 of the firearm and the projectile 20 is in position 28 with forward obturation accomplished. The round of telescoped caseless ammunition is fired by impingement of multiple firing pins 36 driven forward (means not shown) into the primer mixture 16. The action of the multiple firing pins on the combustible primer causes forward and radial friction and crushing action which initiates the primer mixture.

In FIG. 2 the annular cavity 14 filled with standard priming mixture 16 is shown in the base of the propellant charge 10. The base of the projectile 34 is shown housed within the axial bore 12 of the propellant charge 10.

In FIG. 3 a propellant charge 38 is illustrated having an annular cavity 40 in its base. The annular cavity 40 is filled with a standard priming mixture 42, and sealed with a waterproof, combustible seal 44. A projectile 46 is secured in a recess 48 in forward end of the propellant charge. The round of caseless ammunition is chambered by action of the bolt 50 pressing at the base 52 of the propellant charge 38. The priming mixture 42 is initiated by impingement of multiple firing pins 54. The multiple firing pins 54 cause both a forward and radial friction and crushing action which initiates the priming mixture.

A round of caseless ammunition having a combustible primer secured in an annular cavity in the base of the propellant charge permits use of multiple firing pins without orientation of the round. Moreover, the force resulting from initiation of the primer is well distributed over the base of the propellant charge which facilitates breakup of the charge thereby enhancing performance.

The combustible primer employed in this invention can be prepared by charging a wet priming mixture into the annular cavity in the base of the propellant charge. The priming mixture is then dried and covered with a seal. The seal can be made from any waterproof, combustible material such as adhesive-backed foiling paper or it can be prepared from propellant.

The combustible primers can also be pre-prepared in any convenient shape from molded single base, double base, triple base or composite propellant or other combustible material such as paper. A primer body is gen erally prepared, charged with a wet standard primer mixture, dried, and sealed. These combustible primers can be made up in mass quantities at low cost and adhesively secured into the annular cavity at the base of the pro pellant charge as desired. Suitable adhesives include nitrocellulose dissolved in methyl ethyl ketone, epoxy resins, polyisocyanate resins, and cellulose acetate lacquers.

The priming mixture employed with combustible primers contain the usual priming mixture ingredients such as potassium chlorate, antimony sulfide, lead sulphocyanide, trinitro-toluol, or other standard primer ingre dients. The exact composition and amount of priming mixture will depend on the formulation and size of the propellant charge to be ignited, and should be chosen to provide sufficient pressure and heat for reliable ignition of the propellant charge.

The propellant charge can be prepared from a single base, double base, triple base, or composite propellant. The charge can be made by a molding technique wherein small granules of propellant such as granules of smokeless powder are bonded together by a suitable binder. In this method, a mold is filled with granules of propellant, a binder is added, and the mold is pressurized at from about 500 psi. to about 2000 p.s.i. for several seconds to about a minute. The propellant charge is then removed from the mold and dried. A suitable binder for single base, double base and triple base propellant is a mixture of collodian and acetone. A binder suitable for composite type propellants is dependent on the type of composite, but in general it is of the same composition as the binder of the composite propellant.

The projectile is secured to the propellant charge with an adhesive such as nitrocellulose in methyl ethyl ketone, which will form a bond between the projectile and the propellant. Other adhesives which can be used include polyisocyanate resins, epoxy resins, and cellulose acetate lacquers. Where the propellant charge has an axial bore throughout as in the preferred embodiment and the diameter of the projectile is small in relation to the diameter of the bore, it is desirable to use a readily combustible material such as styrofoam to aid in securing the projeo tile. A solid ring or rings of styrofoam, for example, can be adhesively secured to both the projectile and the bore of the propellant charge to secure the projectile therein. Only a small amount of adhesive is required since the function of the adhesive is to prevent the projectile from loosening during handling operations.

The rounds of caseless ammunition of this invention can be prepared in any size desired. The amount of pro pellant in the propellant charge, the caliber of the projectile, and overall round configuration can be determined by one skilled in the art depending on such factors as the firearm for which the round is designed, and the desired range for the projectile.

As will be evident to those skilled in the art, various modifications can be made or followed, in light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or scope of the claims.

What I claim and desire to protect by Letters Patent is:

1. A round of caseless ammunition having in combination a one piece elongated propellant charge having a forward end and a base with an annular cavity defined in said base, a combustible primer secured in said annular cavity and a projectile secured to the propellant charge, said round fired by impingement of multiple firing pins on the annular combustible primer.

2. The round of caseless ammunition of claim 1 wherein the primer is comprised of a standard priming mixture secured in the annular cavity within the base of the propellant charge with a combustible seal.

3. The round of caseless ammunition of claim 1 wherein the primer is pre-prepared, said primer comprised of a primary body filled with standard priming mixture and sealed with a combustible seal, said primar secured within the annular cavity in the base of the propellant charge.

4. The round of caseless ammunition of claim 1 wherein the propellant charge has an axial bore through out, and said projectile is positioned and secured within the axial bore of the propellant charge.

5. The round of caseless ammunition of claim 4 wherein the primer is comprised of a standard primer mixture secured in the annular cavity within the base of the propellant charge with a combustible seal.

6. The round of caseless ammunition of claim 4 wherein the primer is pre-prepared, said primer comprised of a primer body filled with standard priming mixture and sealed with a combustible seal, said primar secured within the annular cavity in the base of the propellant charge.

7. The round of caseless ammunition of claim 4 wherein the entire length of projectile is surrounded by propellant charge.

8. The round of caseless ammunition of claim 7 wherein the propellant charge is comprised of molded granules of smokeless powder.

References Cited UNITED STATES PATENTS Re. 1,455 4/1863 Saarps 102-45 53,168 3/1866 Moffatt 10245 1,856,022 4/1932 Blacker 102F318 X 2,866,412 12/1958 Meyer et a1. 10238 3,320,887 5/1967 Quinlan et al. 102-45 3,345,945 10/1967 Quinlan et a1. 10238 ROBERT F. STAHL, Primary Examiner US. Cl. X.R. 102-45 

